1) Field of the Invention
The present invention relates to a chord detecting device for detecting chords based on information-on-depressed-key obtained at the time that a plurality of keys on a keyboard provided in an electronic musical instrument such as an electronic organ, etc. are depressed, and to an automatic accompaniment-playing apparatus for automatically selecting a desired accompaniment pattern based on a detected chord so as to perform an accompaniment based on the thus-selected accompaniment pattern.
2) Description of the Related Prior Art
A chord detecting apparatus, has heretofore been known in which a designated musical-sound pattern, a pattern-on-depressed-key, etc. is associated with each chord in a 1:1 correspondence to be stored as information in a memory, thereby detecting a desired chord on the basis of the musical-sound pattern, referring to a correspondence table obtained on their relative connection referred to above.
As a method of detecting a desired chord to determine an accompaniment pattern corresponding to the detected chord, there is known one in which each of a number of accompaniment patterns is associated with each of a number of chords in a 1:1 correspondence to be stored as information in a memory, thereby reading or selecting a desired accompaniment pattern corresponding to the detected chord from the memory.
When it is desired to adopt the method in which the pattern-on-depressed-key is associated with each chord in a 1:1 correspondence to detect a desired chord based on the information-on-depressed-key, so as to be stored as information in the memory, this method involves the problem that even when a depression key falls within one octave by way of example, it is necessary to perform a corresponding process of 2 to the twelfth power (4096), and a chord includes component sounds referred to as so-called "tension" (a ninth (9th) chord, an eleventh (11th) chord, a thirteenth (13th) chord, etc.) above one octave, thus resulting in the necessity of providing a large number of correspondence tables if they are included.
In addition, chords referred to as major seventh (maj7th) and minor seventh (min7th) chords are obtained by adding a seventh (7th) musical degree to a major (maj) chord and the same to a minor (min) chord, respectively, each of which comprises three pitch names. Furthermore, if a ninth (9th) musical degree is added to them, those referred to as major ninth (maj9th) and minor ninth (min9th) chords are obtained. Thus, the chords are defined by such combinations referred to above. It is then examined by means of this method whether or not these 7th and 9th are included in the three pitch names forming the chord of the major (maj) or the minor (min). As a consequence, a desired chord may be specified based on the result of its examination.
However, a problem arises in that when the plurality of keys are depressed, it is not clear which sound would be a root, and when keys of the 7th and 9th are also depressed, the chord cannot be specified unequivocally.
On the other hand, when it is desired to prepare an accompaniment pattern corresponding to the type of a chord for each performance mode such as rock, jazz, classics or for each performance section such as an introduction, an ending, normal, a variation, upon selection of an accompaniment pattern corresponding to a chord specified by some method, a mass-storage type memory is required. When the accompaniment pattern is established in such a manner that a performer can input the same, a burden on the process for inputting the same is increased, thereby causing a problem.